1. Field of the Invention
This invention relates to shaft seals, also known as oil seals, designed for sealing against fluid leakage along shafts such as engine crank shafts and motor vehicle drive transmission shafts, and in a preferred embodiment to shaft seals of the type including a metal case and a polytetrafluoroethylene sealing element connected thereto.
2. Description of the Prior Art
Shaft seals of the type including a metal case and a polytetrafluoroethylene sealing element connected thereto are known, however, they are presently made as assembled seals consisting of four component parts including an outer metal shell, an inner metal shell, a gasket and the polytetrafluoroethylene sealing element held in place by means of the outer shell being rolled over and crimped against the inner shell to mechanically hold the sealing element in place. The prior art manufacturing method requires numerous operations and the resulting seal is subject to damage encountered in handling, is subject to leakage between the outer metal case and the sealing element, and has an I.D. to O.D. concentricity problem.
It is an object of the present invention to provide an improved shaft seal of the type including an annular metal case and a polytetrafluoroethylene sealing element connected thereto, and a method for making the same comprising bonding a synthetic rubber filler ring between the metal case and the sealing element such that the filler ring chemically bonds to the metal case and mechanically bonds to the sealing element.
It is another object of the present invention to provide a shaft seal of the type including an annular metal case and a polytetrafluoroethylene sealing element, and a less expensive and faster method for making the same, that eliminates the prior art problems of a leakage route between the metal shell and the sealing element and of an I.D. to O.D. concentricity problem.